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CHEMICAL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 7)
ACS Sustainable Chemistry & Engineering     Hybrid Journal   (Followers: 6)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 5)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Advanced Chemical Engineering Research     Open Access   (Followers: 32)
Advanced Powder Technology     Hybrid Journal   (Followers: 17)
Advances in Applied Ceramics     Hybrid Journal   (Followers: 5)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 26)
Advances in Chemical Engineering and Science     Open Access   (Followers: 57)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 11)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 10)
Applied Petrochemical Research     Open Access   (Followers: 2)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 8)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 15)
Biofuel Research Journal     Open Access   (Followers: 4)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 8)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
Chemical and Engineering News     Free   (Followers: 15)
Chemical and Materials Engineering     Open Access   (Followers: 13)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 13)
Chemical and Process Engineering     Open Access   (Followers: 28)
Chemical and Process Engineering Research     Open Access   (Followers: 24)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 31)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 16)
Chemical Engineering and Science     Open Access   (Followers: 19)
Chemical Engineering Communications     Hybrid Journal   (Followers: 14)
Chemical Engineering Education     Full-text available via subscription  
Chemical Engineering Journal     Hybrid Journal   (Followers: 46)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 25)
Chemical Engineering Research Bulletin     Open Access   (Followers: 12)
Chemical Engineering Science     Hybrid Journal   (Followers: 27)
Chemical Geology     Hybrid Journal   (Followers: 23)
Chemical Papers     Hybrid Journal   (Followers: 2)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 4)
Chemical Reviews     Full-text available via subscription   (Followers: 184)
Chemical Society Reviews     Full-text available via subscription   (Followers: 42)
Chemical Technology     Open Access   (Followers: 16)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry of Materials     Full-text available via subscription   (Followers: 246)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 4)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal   (Followers: 1)
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 1)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
CORROSION     Full-text available via subscription   (Followers: 21)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 37)
Corrosion Reviews     Hybrid Journal   (Followers: 6)
Crystal Research and Technology     Hybrid Journal   (Followers: 6)
Current Opinion in Chemical Engineering     Open Access   (Followers: 7)
Designed Monomers and Polymers     Open Access   (Followers: 2)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
Eksergi     Open Access  
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 6)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Food and Environment Safety     Open Access  
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 2)
Gels     Open Access  
Geochemistry International     Hybrid Journal   (Followers: 2)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 6)
Heat Exchangers     Open Access   (Followers: 3)
High Performance Polymers     Hybrid Journal   (Followers: 1)
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 5)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 10)
Indonesian Journal of Chemical Science     Open Access   (Followers: 1)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 12)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 23)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Gases     Open Access  
Info Chimie Magazine     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Engineering     Open Access   (Followers: 7)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 5)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 3)
International Journal of Industrial Chemistry     Open Access   (Followers: 1)
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 6)
International Journal of Waste Resources     Open Access   (Followers: 4)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 5)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 6)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 14)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 138)
Journal of Applied Science & Process Engineering     Open Access  
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 12)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 7)
Journal of Chemical Engineering     Open Access   (Followers: 20)
Journal of Chemical Engineering and Materials Science     Open Access   (Followers: 2)
Journal of Chemical Science and Technology     Open Access   (Followers: 5)
Journal of Chemical Sciences     Partially Free   (Followers: 22)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 17)
Journal of CO2 Utilization     Hybrid Journal   (Followers: 2)
Journal of Combinatorial Chemistry     Full-text available via subscription   (Followers: 1)
Journal of Crystallization Process and Technology     Open Access   (Followers: 8)
Journal of Environmental Chemical Engineering     Hybrid Journal   (Followers: 7)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Processing & Technology     Open Access   (Followers: 1)
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 1)
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (Followers: 1)
Journal of Information Display     Hybrid Journal   (Followers: 1)
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 9)
Journal of Materials Science and Chemical Engineering     Open Access  
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 6)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 8)
Journal of Organic Semiconductors     Open Access   (Followers: 5)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 5)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 6)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 9)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 6)
Journal of Polymers     Open Access   (Followers: 6)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 2)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 321)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Brazilian Chemical Society     Open Access   (Followers: 2)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 2)
Journal of the Taiwan Institute of Chemical Engineers     Hybrid Journal   (Followers: 2)
Journal of Water Chemistry and Technology     Hybrid Journal   (Followers: 9)
Jurnal Bahan Alam Terbarukan     Open Access  
Jurnal Inovasi Pendidikan Kimia     Open Access   (Followers: 5)
Jurnal Reaktor     Open Access  
Jurnal Rekayasa Kimia & Lingkungan     Open Access  
Jurnal Teknologi Dan Industri Pangan     Open Access   (Followers: 1)
Konversi     Open Access  
Korean Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 2)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 16)
Materials Science and Applied Chemistry     Open Access  
Materials Sciences and Applied Chemistry     Full-text available via subscription  
Modern Chemistry & Applications     Open Access  
Molecular Imprinting     Open Access  
Nanochemistry Research     Open Access  
Nanocontainers     Open Access   (Followers: 1)
Nanofabrication     Open Access  
Noise Control Engineering Journal     Full-text available via subscription   (Followers: 4)
Ochrona Srodowiska i Zasobów Naturalnych : Environmental Protection and Natural Resources     Open Access  
Petroleum Chemistry     Hybrid Journal   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 4)
Plasma Processes and Polymers     Hybrid Journal   (Followers: 3)
Plasmas and Polymers     Hybrid Journal  
Polymer     Hybrid Journal   (Followers: 129)
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 16)
Polyolefins Journal     Open Access  
Powder Metallurgy Progress     Unknown   (Followers: 1)
Powder Technology     Hybrid Journal   (Followers: 13)
Recyclable Catalysis     Open Access   (Followers: 1)
Research on Chemical Intermediates     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 4)
Revista ION     Open Access  
Revista Mexicana de Ingeniería Química     Open Access  
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Bulletin     Hybrid Journal   (Followers: 2)
Russian Journal of Applied Chemistry     Hybrid Journal   (Followers: 1)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Solid Fuel Chemistry     Hybrid Journal  
South African Journal of Chemical Engineering     Open Access   (Followers: 2)
South African Journal of Chemistry     Open Access   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Sustainable Chemical Processes     Open Access   (Followers: 2)
Synthesis Lectures on Chemical Engineering and Biochemical Engineering     Full-text available via subscription  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 4)
The Chemical Record     Hybrid Journal   (Followers: 1)
Theoretical Foundations of Chemical Engineering     Hybrid Journal   (Followers: 2)
Transition Metal Chemistry     Hybrid Journal   (Followers: 4)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Visegrad Journal on Bioeconomy and Sustainable Development     Open Access   (Followers: 2)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)


Journal Cover Chemical Engineering Science
  [SJR: 1.073]   [H-I: 135]   [27 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [3118 journals]
  • CFD modeling of the influence of carrier thermal conductivity for
           structured catalysts in the WGS reaction
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): V. Palma, D. Pisano, M. Martino
      This work describes a CFD modeling study of the Water Gas Shift single stage process in adiabatic conditions, operated by COMSOL Multiphysics 5.0, by means of two different catalytic configurations; the real novelty was to show that the use of structured catalysts with high thermal conductivity could greatly improve the performances of the whole process. The simulations are then validated with kinetic data reported in a previous work, and provides a useful springboard for the design of a single stage process. It was demonstrated that the use of highly conductive carriers reduces the difference of temperature throughout the catalytic bed, under adiabatic conditions, by means of a backdiffusion of the heat of reaction from the output to the input of the bed. The redistribution allows to increase the inlet temperature, with a benefit for the kinetics, at the expence of the outlet temperature that, decreasing, promotes the thermodynamics. The use of a highly active catalytic formulation, at low temperatures, coupled with a conductive carrier, provides, in principle, the possibility to realize a strong intensification of the process.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Fluid dynamic evaluation of a 10 MW scale reactor design for chemical
           looping combustion of gaseous fuels
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Michael Stollhof, Stefan Penthor, Karl Mayer, Hermann Hofbauer
      The design of an efficient and scale-up ready reactor system is, together with development of a high performance oxygen carrier, one of the most important research topics in chemical looping combustion. The dual circulating fluidized bed (DCFB) concept is a reactor concept consisting of two interconnected circulating fluidized beds, air and fuel reactor, where the oxygen carrier is the bed material. In the present study a so-called cold flow model is used to investigate the fluid dynamic behavior of a next scale design based on the DCFB concept (10 MW fuel power input) in order to optimize the system design. Four different designs of the fuel reactor are investigated with focus on the solid distribution and general operating parameters and their influence on the operating range. For that purpose, several parameters like e.g. the amount of fluidization gas for both reactors, the total solid inventory, and the fuel power, are variated. Pressure profiles are used to get a comprehensive overview of the fluid dynamic behavior of the different reactor designs. Comparison of the fuel reactor designs shows that operation of the air reactor is not affected by changes of the fuel reactor design. In contrast significant changes, especially in the solid distribution, are recognizable for the different fuel reactor designs. These changes concern mainly the adapted sections of the fuel reactor. Two of the proposed fuel reactor designs are limited in their operating range due to unstable operating conditions, caused by fluid dynamic effects. At such unstable operating conditions the solid inventory distribution between both reactors fluctuates. This behavior is caused by the geometry of the fuel reactor. Further, due to variations in the geometry of the fuel reactor effects leading to the unstable operating conditions are identified. However, unstable operating conditions are caused by the shape of the conical form of the bottom part of the fuel reactor.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Prediction of fluid flow through and jet formation from a high pressure
           nozzle using Smoothed Particle Hydrodynamics
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Gerald G. Pereira, Paul W. Cleary, Yoshihiro Serizawa
      This paper reports on the development and evaluation of an SPH (Smoothed Particle Hydrodynamics) model for high pressure water flow through and from a nozzle and prediction of its break up into a spray of high speed water droplets. This appears to be the first application of the SPH technique to fully model a high pressure nozzle. The model predicts the internal flow and pressure distribution and enables exploration of the role of the internal geometric insert used in this design of the nozzle. It also predicts exit velocities from the nozzle as well as the pressure distribution generated by the nozzle and droplet size distribution of the resulting spray. Three different nozzle inflow rates were simulated and for all cases the numerical simulation of nozzle and spray gave generally good agreement with experiments, but complete agreement was not achieved. For better agreement, higher resolution for the SPH solution is required. The SPH simulations also show the role that the insert in the nozzle has on the flow and the resulting jet. It produces a flat inclined high velocity liquid jet within the second half of the nozzle which will generate turbulent eddies that may enhance the nucleation of the droplets in the fragmenting jet after it exits the nozzle. Overall, SPH has been shown to have a very good capacity to model high pressure nozzles and with further refinements of the technique should be able to yield accurate, quantitative data.

      PubDate: 2017-12-27T05:46:41Z
  • Two-directional concurrent strategy of mode identification and sequential
           phase division for multimode and multiphase batch process monitoring with
           uneven lengths
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Shumei Zhang, Chunhui Zhao, Furong Gao
      In general, batch processes cover two-directional dynamics, in which the batch-wise dynamics are related to different operation modes, while the time-wise variations correspond to different phases within each batch. The problem of unevenness is common as a result of various factors, particularly in multimode batch processes. In order to address these issues, this paper proposes a two-directional concurrent strategy of mode identification and sequential phase division for multimode and multiphase batch process monitoring with the uneven problem. Firstly, pseudo time-slices are constructed in order to describe the process characteristics regarding the sample concerned, which can preserve the local neighborhood information within a constrained searching range and effectively prevent the synchronizing problem caused by uneven lengths. Secondly, mode identification is conducted along the batch direction and the phase affiliation is sequentially determined along time direction by determining the changes in variable correlations. The two-directional steps are implemented alternatively in order to identify the mode and phase information, which can also guarantee the time sequence within each mode. Thirdly, for online monitoring, the mode information and phase affiliation are simultaneously judged in real time for each new sample, from which the fault status is distinguished from the phase shift. The division results can indicate the critical-to-mode phases from which a certain mode begins to be separated into different sub-modes. In order to illustrate the feasibility and effectiveness of the proposed algorithm, it is applied to a multimode and multiphase batch process (namely an injection molding process) with the uneven problem.

      PubDate: 2017-12-27T05:46:41Z
  • Impedance spectroscopy and membrane potential analysis of microfiltration
           membranes. The influence of surface fractality
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Darío Ramón Díaz, Francisco Javier Carmona, Laura Palacio, Nelio Ariel Ochoa, Antonio Hernández, Pedro Prádanos
      In this work, the proper charge density of a microfiltration membrane has been determined by using two different methods. Firstly, the ionic transport of a KCl solution has been investigated by simultaneous measurements of saline flux and membrane potential (MP) resulting from a concentration gradient through the membrane. A simple model, including all the relevant contributions to the global electrical potential drop, allowed a calculation of transport numbers and membrane charge density. The response of ions inside the membrane to an oscillating electrical potential has been analyzed by impedance spectroscopy (or electrical impedance spectroscopy EIS). A quite simple experimental EIS design allowed, by taking into account MP measurements too, an easy assignation of an equivalent circuit. After a careful analysis of EIS results, it was possible to evaluate the electrical conductivity inside the pores and the charge density. Both were found to be quite similar to the values obtained from MP alone. This agreement of EIS results with the MP ones, that are much simpler to deal with, confirms the accuracy of EIS to study the electrical properties of microfiltration membranes. The influence of electrode roughness and, in our EIS cell, the membrane roughness, on the constant phase element (CPE) of the equivalent circuit has been proved. Within this frame, the roughness fractal dimension of the membrane surface could be determined from EIS measurements. It resulted in fair agreement with the atomic force microscopy (AFM) determination.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Synthesis of mass exchanger networks in a two-step hybrid optimization
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Michael Short, Adeniyi J. Isafiade, Lorenz T. Biegler, Zdravko Kravanja
      We present a new method for the synthesis of mass exchanger networks (MENs) involving packed columns. Simultaneous synthesis of MENs is typically done through the use of mixed-integer nonlinear program (MINLP) optimization, with simplifications made in the mathematical representations of the exchangers due to computational difficulty in solving large non-convex mixed-integer problems. The methodology proposed in this study makes use of the stage-wise based superstructure MINLP formulation for the network synthesis. This stage-wise superstructure model incorporates fixed mass transfer coefficients, fixed column diameters, no pressure drops, and unequal compositional mixing for models. In this paper, the simplified MINLP model is further improved by including a detailed individual packed column design in a non-linear programming (NLP) sub-optimization step, where orthogonal collocation is utilized for the partial differential equations, and optimal packing size, column diameter, column height, pressure drops, and fluid velocities. Detailed designs are then used to determine correction factors that update the simplified stage-wise superstructure models to more accurately portray the chosen design. Once the MINLP is updated with these correction factors, the model is re-run, with new correction factors obtained. This iterative procedure is repeated until convergence between the objective function of the MINLP and that of the NLP sub-optimization is achieved, or until a maximum number of iterations is reached. The methodology is applied to two examples and is shown to be robust and effective in generating new topologies, and in finding superior networks that are physically realizable.

      PubDate: 2017-12-27T05:46:41Z
  • Efficient surface modification of thin-film composite membranes with
           self-catalyzed tris(2-aminoethyl)amine for forward osmosis separation
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Liang Shen, Yan Wang
      Interfacially synthesized polyamide (PA) thin-film composite (TFC) membranes are widely employed in forward osmosis (FO) applications because of the easy fabrication and excellent separation performance. But they generally suffer from the relative low water permeability and high fouling tendency due to the inherent hydrophobic nature of the PA layer. In this study, an efficient surface modification of nascent TFC membranes is performed by grafting a self-catalyzed tripodal amine—tris(2-aminoethyl)amine (TAEA), in order to improve the membrane performance. This tertiary amine plays a dual role of the reactive amine monomer reacting with acyl chloride groups and the catalyst accelerating the amidation reaction between 1,3,5-trimesoyl chloride (TMC) and TAEA, therefore contributing to an efficient grafting effect to the greatest extent. State-of-the-art characterizations are applied to verify the modification mechanism. The effects of the pH and concentration of the TAEA solution on the overall properties of the resultant TFC membranes are systematically investigated, including the surface chemical composition, surface morphology, hydrophilicity, surface charge, separation performance, and fouling resistance. Compared with the control TFC membrane, TAEA-modified TFC membranes exhibit significantly improved water fluxes, higher antifouling propensity, and comparable reverse salt fluxes.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Cellulose-based membranes via phase inversion using [EMIM]OAc-DMSO
           mixtures as solvent
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Elif Nur Durmaz, P. Zeynep Çulfaz-Emecen
      Cellulose and cellulose acetate membranes were fabricated by phase inversion from their solutions in 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc), or its mixture with dimethyl sulfoxide (DMSO). Inclusion of DMSO in the solution decreased crystallinity and rejection for both polymers. When cellulose solutions were coagulated in ethanol crystallinity and rejections were lower, and cellulose acetate membranes coagulated in ethanol had a loose, macroporous morphology, which was attributed to the poor nonsolvent strength of ethanol for this polymer. All cellulose membranes, when dried, performed similarly in rejecting Blue Dextran (20 kDa) by over 90% and Bromothymol Blue by around 80%. On the other hand, when these membranes were used without drying, Bromothymol Blue rejections decreased with increasing DMSO content in solution and with changing of nonsolvent from water to ethanol, implying the presence of a microporous structure which collapses to a similar dense structure upon drying for all cases. Phase inversion rate of both polymers was slower in ethanol, which was attributed to the lower diffusivity of ethanol compared to water due to its larger size. The viscosity of the solvent media, which differed by an order of magnitude between [EMIM]OAc and [EMIM]OAc-DMSO mixtures, on the other hand, did not have a measurable influence on the phase inversion rate.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Quantitative measurements of capillary absorption in thin porous media by
           the Automatic Scanning Absorptometer
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): C.J. Kuijpers, T.A.P. van Stiphout, H.P. Huinink, N. Tomozeiu, S.J.F Erich, O.C.G. Adan
      A 1D model based on Darcy’s law is proposed to allow quantitative measurements of the penetration depth of water-glycerol-hexanediol mixtures in thin porous media using an Automatic Scanning Absorptometer (ASA). The limitations of this 1D model are discussed with respect to the nozzle dimensions and the liquid penetration depth. The penetration depth scales with liquid (viscosity and surface tension (η, σ)) and media parameters (average pore radius (r)) as predicted by Darcy’s law for Al2O3 disks that are inert to the liquid components. The penetration dynamics in PVDF and MCE filter membranes show a deviation from Darcy’s law, indicating specific liquid – media interaction with at least one of the liquid components. Furthermore a linear time regime is observed in the early stages of liquid penetration for time scales much larger than for which inertia effects are expected. This can on the one hand indicate that either, the liquid does not move into the fibrous samples as a homogenous liquid, or that the porous material deforms during the liquid imbibition process. On the other hand, it could be an effect resulting from the complexity of the porous structure itself and an indication of surface film flow formation.

      PubDate: 2017-12-27T05:46:41Z
  • Bridging the gap across scales: Coupling CFD and MD/GCMC in polyurethane
           foam simulation
    • Abstract: Publication date: 16 March 2018
      Source:Chemical Engineering Science, Volume 178
      Author(s): Mohsen Karimi, Daniele Marchisio, Erik Laurini, Maurizio Fermeglia, Sabrina Pricl
      This work presents a multi-scale approach to reacting and expanding polyurethane (PU) foams modeling and simulation. The modeling strategy relies on two pillars: an atomistic model (molecular dynamics (MD)/Grand Canonical Monte Carlo (GCMC)) that provides liquid mixture density and reactant solubility and a continuum model (CFD) in which the expansion characteristics of the foam is modeled exploiting the results of the atomistic simulations. The resulting coupled model is validated for two different PU systems applied in four batches with chemical and physical blowing agents. The results demonstrate the efficacy and reliability of the developed model in the simulation of different PU foam properties such as apparent density and temperature evolutions.

      PubDate: 2017-12-27T05:46:41Z
  • State estimation for a penicillin fed-batch process combining particle
           filtering methods with online and time delayed offline measurements
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Julian Kager, Christoph Herwig, Ines Viktoria Stelzer
      Real time monitoring of physiological characteristics during a cultivation process is of great importance in the pharmaceutical industry. Measuring biomass, product, substrate and precursor concentrations continuously however is limited due to time-consuming laboratory analysis or expensive and hard-to-handle devices. In this work, a particle filter algorithm for estimating these difficult-to-measure process states in a Penicillium chrysogenum fed-batch cultivation is presented. The implemented particle filter represents a new algorithmic framework, combining several already existing methods and techniques for state estimation. It is based on nonlinear process and measurement models and takes into account both online measurements for state estimation and time delayed offline measurements, ensuring the observability of the considered system and being essential for the adaptation of dynamic model parameters. The application on real experimental data showed the convincing performance of the algorithm, estimating biomass, precursor and product concentration, as well as the specific growth rate, requiring standard measurements only. Furthermore, the positive effect of parameter estimation with respect to estimation quality was analyzed and the effect of the time delay was highlighted exemplarily. Despite of being computationally expensive due to time delayed data, the algorithm can be considered as an alternative monitoring strategy for industrial applications. Thus, it can be used further for process understanding and control.

      PubDate: 2017-12-27T05:46:41Z
  • Construction of thermo-tolerant yeast based on an artificial protein
           quality control system (APQC) to improve the production of bio-ethanol
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Ke Xu, Liping Yu, Wenxin Bai, Bing Xiao, Yueqin Liu, Bo Lv, Jun Li, Chun Li
      A major challenge for the production of bio-ethanol is to develop yeast that can sustain growth under high temperature. Here, we show the application of an artificial protein quality control (APQC) system to an industrial Saccharomyces cerevisiae strain for improving thermo-tolerance, a key trait for a bio-ethanol fermentation program. All engineered strains exhibited a significantly higher growth rate and cell viability at 37 °C, which conferred increased thermo-tolerance and more efficient glucose conversion to ethanol. Furthermore, the analysis of ubiquitination and the enzyme activities of pyruvate kinase (PK) and malate dehydrogenase (MDH) indicated strengthened protein quality, implying that proteostasis had been effectively improved at higher temperature. Industrial material fermentation results from yeast-RSP5-UBC4 (combined expression of ubiquitin conjugated enzyme E2 and ubiquitin ligase E3) showed a 2.4% increase in ethanol production. All these findings prove that APQC is suitable for improving yeast resistance to high temperature during industrial bio-ethanol production.

      PubDate: 2017-12-27T05:46:41Z
  • Bio-combustion of petroleum coke: The process integration with
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Ihana A. Severo, Mariany C. Deprá, Juliano S. Barin, Roger Wagner, Cristiano R. de Menezes, Leila Q. Zepka, Eduardo Jacob-Lopes
      The objective of this study is to develop a bio-combustion system integrated into a photobioreactor. Different oxidizers (a simulated industrial gas stream containing 5.5% O2, 18% CO2 and 76.5% N2, the atmospheric air and the photobioreactor exhaust gases in different residence times) were injected into the combustion chamber, and combustion temperature, combustion stability, heating rate, and fuel conversion were analyzed. The results have shown that the use of photobioreactor exhaust gases as oxidizer, biofuel, and nitrogen diluent in the combustion furnace, have increased the thermal efficiency of the system, with heating rates 30.5% and 45.8% higher than the atmospheric air and the simulated industrial gas stream, respectively. Thus, the integration of these processes could be considered a viable strategy to improve the combustion systems thermal performance, efficiently contributing to the sustainability and economy of industrial operations.

      PubDate: 2017-12-27T05:46:41Z
  • Effect of calcium on the fouling of whey protein isolate on stainless
           steel using QCM-D
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Wang Yang, Dan Li, Xiao Dong Chen, Ruben Mercadé-Prieto
      Fouling is a ubiquitous problem in the food industry yet details are scarce on how such deposits grow with time to unsustainable levels; processes have to be stopped and equipment cleaned, both at a great cost. Proper understanding of fouling rates, through mechanistic models, would help developing strategies to minimize fouling. In this study, we consider the deposition over stainless steel similar to 316 of whey proteins as a model fouling material in the dairy industry. Fouling rates were determined using quartz crystal microbalance with dissipation monitoring (QCM-D) at 55–65 °C for >2 h. The key parameter studied is the effect of the calcium concentration, largely uncontrolled in the past but which recent studies suggest to be as important as temperature. The present QCM-D results confirm and detail the great enhancement effect of calcium in whey fouling, even at the low temperatures tested, increasing the fouling rates by more than hundred times at free calcium concentrations of 40–80 mg/L.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Particle motion and heat transfer in an upward-flowing dense particle
           suspension: Application in solar receivers
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): P. García-Triñanes, J.P.K. Seville, R. Ansart, H. Benoit, T.W. Leadbeater, D.J. Parker
      Concentrated solar power (CSP) plants conventionally make use of molten salt as the heat transfer medium, which transfers heat between the solar receiver and a steam turbine power circuit. A new approach uses particles of a heat-resistant particulate medium in the form of many dense upward-moving fluidised beds contained within an array of vertical tubes within the solar receiver. In most dense gas–solid fluidisation systems, particle circulation is induced by bubble motion and is the primary cause of particle convective heat transfer, which is the major contributing mechanism to overall heat transfer. The current work describes experiments designed to investigate the relationship between this solids convection and the heat transfer coefficient between the bed and the tube wall, which is shown to depend on the local particle concentration and their rate of renewal at the wall. Experiments were performed using 65 µm silicon carbide particles in a tube of diameter 30 mm, replicating the conditions used in the real application. Solids motion and time-averaged solids concentration were measured using Positron Emission Particle Tracking (PEPT) and local heat transfer coefficients measured using small probes which employ electrical resistance heating and thermocouple temperature measurement. Results show that, as for other types of bubbling beds, the heat transfer coefficient first increases as the gas flow rate increases (because the rate of particle renewal at the wall increases), before passing through a maximum and decreasing again as the reducing local solids concentration at the wall becomes the dominant effect. Measured heat transfer coefficients are compared with theoretical approaches by Mickley and Fairbanks packet model and Thring correlation. The close correspondence between heat transfer coefficient and solids movement is here demonstrated by PEPT for the first time in a dense upward-moving fluidised bed.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Pore-scale simulation of vortex characteristics in randomly packed beds
           using LES/RANS models
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Jiang Linsong, Liu Hongsheng, Wu Dan, Wang Jiansheng, Xie Maozhao
      Turbulent flow characteristics and vortex behaviors in the pore space of real packed beds under different flow conditions is numerically investigated. Real geometric structure of randomly packed beds is modeled using the discrete element software LIGGGHTS. Both LES and RANS methods are employed to predict vortex shape and evolution features at pore scale in actual packed beds. The numerical model is validated corresponding to experimental data, a good agreement is achieved between predicted results and measurements. Based on the computational results, the distribution characteristics of vorticity and velocity in multiple representative special structures are analysed, such as the channel formed by two pellets, similar triangle area formed by compact spherical walls and channel. Besides the effects of special structures on vortex shape and turbulence intensity is studied, such as the guiding and friction effect by the side spherical wall on gas motion, and strong shear force on both sides of the main channel. The Q criterion is used to identify vortex structures and capture distribution and evolution of vortexes in the computational domain. Moreover, the effect of inlet velocity on the position and shape of eddies is investigated, and eddy morphological changes under unsteady inlet conditions are also discussed., At last, a comparison between LES and RANS methods shows that the LES method can capture more details of the distribution and shape of the vortexes in the pore space, and therefore it is more suitable to the complicated flow field in porous media.

      PubDate: 2017-12-27T05:46:41Z
  • Self-agglomeration mechanism of iron nanoparticles in a fluidized bed
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Jun Li, Jing Kong, Shengyi He, Qingshan Zhu, Hongzhong Li
      Aided by self-agglomeration, a two-stage reduction process conducted at a higher temperature (600 °C) than the single-stage process resulted in an enhancement of the k constant to more than twice that of the single-stage process. A force balance model coupled with the reduction kinetics of Fe2O3 is first proposed to explain the self-agglomeration mechanism of iron nanoparticles (NPs) during the reduction. This force balance model successfully elucidates the reason for the prevention of defluidization via a two-stage fluidized bed method. At lower temperatures, there is a long stationary phase, which is of great importance in overcoming the sintering of agglomerates and in promoting the reduction reaction. At lower temperatures, the initial NPs first self-agglomerate into particles that are tens of microns in size; they then gradually agglomerate into larger particles (>100 μm) at higher temperatures. By contrast, the sudden growth of iron NP agglomerates causes sintering and defluidization in the single-stage fluidized bed method.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Pinch-off of liquid bridge during droplet coalescence under constrained
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Leqin Peng, Zhengyuan Luo, Yi Y. Zuo, Gang Yan, Bofeng Bai
      In this study, we perform an experimental investigation on the dynamical behaviors of a liquid bridge formed during droplet coalescence. Notably, the two droplets are constrained respectively by two vertically aligned needles. Of particular interest is the pinch-off of the liquid bridge under this constrained condition. We observe three typical behaviors of the liquid bridge: (1) reaching a stable shape after damped oscillations (regime I); (2) pinching off at both sides in the first necking stage with the largest oscillation amplitude (regime II); and (3) pinching off at only the upper side after once or twice necking (regime III). To indicate the condition when the pinch-off of the liquid bridge may occur, we develop a phase diagram based on the radius ratio of the droplet to the needle Rd /Rn and the Bond number Bo, which respectively characterizes the relative importance of surface tension to the constraint force from needles and that of gravity to surface tension. In general, the dynamical behavior of the liquid bridge transitions from regime II to regime I with Rd /Rn decreasing, and the critical value for this transition is 1.6. This transition indicates that the constraint force keeps the liquid bridge stable while the surface tension promotes its instability. Surprisingly, once the Bond number is sufficiently high (e.g., Bo > 0.05), regime III (i.e., pinch-off at only the upper side) is observed when Rd /Rn becomes around the regime II to I transition (i.e., Rd /Rn  = 1.6). It is because the effect of gravity becomes predominant over the surface tension and the constrained force from needles. Moreover, we analyze the pinch-off characteristics of the liquid bridge lying in regimes II and III, including its pinch-off time (i.e., the time interval from the formation and pinch-off of the liquid bridge) and its neck shape at the instant of pinching off.

      PubDate: 2017-12-27T05:46:41Z
  • Modeling and validation of a pilot-scale aqueous mineral carbonation
           reactor for carbon capture using computational fluid dynamics
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Minjun Kim, Jonggeol Na, Seongeon Park, Jong-Ho Park, Chonghun Han
      In anticipation of the successful establishment of carbon capture, utilization, and storage (CCUS) technology, a pilot-scale aqueous mineral carbonation plant, that removes CO2 through a reaction with a Ca(OH)2 solution, was built in Incheon, South Korea. Using computational fluid dynamics (CFD), two reactors with a diameter of 2.2 m and a height of 6.0 m were modeled and validated for reactor scale-up and optimization. Because a direct simulation of bubble breakage, coalescence, and interphase mass transfer results in enormous computational costs for modeling the pilot-scale multiphase reactor, a CFD-lumped correlation model was introduced to simulate a large reactor; this resulted in acceptable computational costs and maintained the simulation accuracy. In order to ensure the acceptability of the CFD model, two-step verification was conducted. The CFD model results were compared with the experimental data and published empirical correlations with regard to the gas holdup, interfacial area, and mass transfer coefficient. Subsequently, the CO2 removal efficiencies of the CFD model were compared with the pilot-plant data. The errors of the CFD model for three hydrodynamic parameters and the CO2 removal efficiencies were in the range of 1–8%. The validated CFD model will be used for designing a four times larger mineral carbonation reactor, that will be built in 2017.

      PubDate: 2017-12-27T05:46:41Z
  • Optimization of pre-concentration, entrainer recycle and pressure
           selection for the extractive distillation of acetonitrile-water with
           ethylene glycol
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Xinqiang You, Jinglian Gu, Vincent Gerbaud, Changjun Peng, Honglai Liu
      We optimize the extractive distillation process for separating the acetonitrile – water azeotropic mixture with ethylene glycol by using a multi-objective genetic algorithm for minimizing under purity constraints the total cost, the energy consumption and the separation efficiency. For the first time we have shown the interest of five aspects by considering them simultaneously (1) the pre-concentration column has been included and (2) there is no need to set a distillate composition constraint (like being at the azeotropic composition) in the pre-concentration column. (3) The operating pressure should be lower than 1 atm because it enhances the relative volatility for 1.0-1a class system. (4) A closed loop optimization must be run, to handle the effect of impurity in the entrainer recycle since too much impurity limits the main product recovery and purity from the extractive column. (5) All three columns process must be optimized together rather than sequentially and with multiple objectives. The studied system belongs to class 1.0-1a and the impurity of the recycled entrainer has strong effect on the purity of acetonitrile product. Overall, 17 variables are optimized; column trays, all feed locations, refluxes, entrainer flow rate and all distillate products; under purity constraints for the acetonitrile and water product and for the entrainer recycle impurity. Among nearly 400 designs satisfying the purity specifications, the design case 3 shows an energy consumption and TAC reduced by more than 20% than a literature reference case, thanks to smaller entrainer flow rate, a reduction of 32 trays and lower operating pressures. The best design is a trade-off between first a feasibility governed by thermodynamics through composition profiles and relative volatility maps and second process cost and energy demands.

      PubDate: 2017-12-27T05:46:41Z
  • Application of hot-wire anemometry for experimental investigation of flow
           distribution in micro-packed bed reactors for synthesis gas conversion
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Farbod Dadgar, Hilde J. Venvik, Peter Pfeifer
      The knowledge of the flow distribution inside microstructured reactors is valuable e.g. for improving the reactor design, developing flow distributors, and optimizing the catalyst loading method. The applicability of the hot-wire anemometry (HWA) technique for experimental determination of the flow distribution inside a multi-stack micro-packed bed reactor is demonstrated for the first time. The anemometry data is then evaluated in relation to the reactor performance for methanol synthesis under relevant industrial operating conditions. A 400 µm long hot-wire connected to a constant temperature anemometer was applied for scanning the flow out of a specially designed reactor model, clamped on a motorized table equipped with a precise positioning system. The anemometry measurements revealed a nonuniformity in the catalyst packing, partially resulting from the reactor design. The flow distribution is poorer for smaller particles and for wider particle size distributions, and worsens as the superficial flow velocity (and the pressure drop) decreases. The effects of the packing nonuniformity on the reactor performance appear minor under methanol synthesis conditions. They could, however, turn out significant upon pushing the overall conversion in the whole reactor towards equilibrium as the synthesis reaction is exothermic, and temperature increase does alleviate the problem. The reactor design should be modified instead.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • VUV/TiO2 photocatalytic oxidation process of methyl orange and
           simultaneous utilization of the lamp-generated ozone
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Wai Szeto, Jiantao Li, Haibao Huang, Dennis Y.C. Leung
      A photocatalytic reactor using an ozone-generating mercury vapor lamp with the capability to simultaneously utilize the ozone internally generated from the lamp was fabricated. The reactor included a microbubble-generating mechanism to facilitate the dissolution of ozone and oxygen in the reaction liquid. Photocatalytic and photolytic degradation were investigated using two types of mercury vapor lamps: an ozone-generating lamp emitting at both 254 nm and 185 nm as well as a germicidal lamp emitting only at 254 nm. The roles of ozone, 254 nm light and 185 nm light under the degradation of methyl orange were investigated. In particular, the mineralization of methyl orange in different processes, namely pure ozonation, photolysis under an ozone-generating lamp with or without the assistance of ozone, photolysis under a germicidal lamp, TiO2 photocatalysis under an ozone-generating lamp with or without the assistance of ozone and TiO2 photocatalysis under a germicidal lamp, were analyzed with the chemical oxygen demand and UV–visible absorption measurements.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • A kinetics study on cumene oxidation catalyzed by carbon nanotubes: Effect
           of N-doping
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Chunlin Mu, Yonghai Cao, Hongjuan Wang, Hao Yu, Feng Peng
      Selective oxidation of hydrocarbons is of great industrial importance. Nanocarbons are recently found highly active for the aerobic oxidation of cumene. In this work, a detailed kinetics study of cumene oxidation catalyzed by carbon nanotubes (CNTs) and nitrogen doped CNTs (NCNTs) was carried out to disclose the crucial influence of N doping in the cumene oxidation. A kinetics model based on the radical reaction mechanism of cumene oxidation was developed, which contained 7 major elementary steps. The kinetics parameters of cumene oxidation upon CNTs and N-doped CNTs (NCNTs) were obtained by the non-linear aggression of the experimental concentration–time data. Mechanistic insights into the effect of N-doping on carbon catalysis were achieved by comparing the kinetics parameters of CNTs and NCNTs. The decomposition of ROOH was found to be the rate-determine step of the cumene oxidation. The nitrogen doping could reduce the activation energy of CHP decomposition, thereby could remarkably accelerate the overall reaction rate of cumene oxidation. The nitrogen doping could also strengthen the interactions between O2, RO , RO2 and the carbon catalysts. Hence, the selectivities to acetophenone and 2-benzyl-2-propanol were improved. This study provides the insight towards the catalytic role of N dopants in the aerobic oxidation of cumene.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • H5PMo10V2O40 anchor by OH of the Titania nanotubes: Highly efficient
           heterogeneous catalyst for the direct hydroxylation of benzene
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Hefang Wang, Cunyue Wang, Meng Zhao, Yongfang Yang, Luping Fang, Yanji Wang
      An efficient catalyst for the direct hydroxylation of benzene to phenol with H2O2 was prepared via the anchor of H5PMo10V2O40 (PMoV2) by OH of Titania nanotubes (TNT) via electrostatic interaction between the Keggin unit of PMoV2 and OH. The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state 31P nuclear magnetic resonance (solid-state 31P NMR), X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis (TGA) demonstrated that PMoV2 was successfully immobilized on the surface of Titania nanotubes by electrostatic interaction. The textural and morphology of PMoV2/Titania nanotubes were characterized by N2 adsorption-desorption, scanning electronic micrograph (SEM) and transmission electron microscope (TEM). PMoV2/Titania nanotubes shows excellent catalytic performance in the hydroxylation of benzene with a 27.3% benzene conversion and 99.1% selectivity to phenol. The results of contact angle and adsorption experiments demonstrate that excellent catalytic performance is attributed to the confinement effect of Titania nanotubes with the nanotube structure and hydrophobic microenvironment, which effectively disperse PMoV2 and concentrate the reactants as well as decrease intrinsic mass transfer resistance. The anchor effect of OH stabilizes and inhibits the leak of PMoV2, leading to good catalytic recyclability with almost unchanged catalytic efficiency after six recycling tests in the acid reaction condition.

      PubDate: 2017-12-27T05:46:41Z
  • Investigation of reaction mechanisms in the chemical vapor deposition of
           al from DMEAA
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): George M. Psarellis, Ioannis G. Aviziotis, Thomas Duguet, Constantin Vahlas, Eleni D. Koronaki, Andreas G. Boudouvis
      We propose a novel reaction scheme for the chemical vapor deposition (CVD) of Al films on substrates from dimethylethylamine alane (DMEAA), supported by the prediction of the Al deposition rate as a function of process temperature. The scheme is based on gas phase oligomerizations of alane which form a substantial amount of intermediates. Combined with reversible surface dehydrogenation steps, the global deposition reaction is composed of a set of 12 chemical reactions. This new scheme entails four intermediates and includes side reactions that play an important role in the formation of Al thin films. The chemistry mechanism is incorporated in a 2D Computational Fluid Dynamics (CFD) model of the CVD reactor setup used for the experimental investigation. The simulation predictions of the Al deposition rate are in good agreement with corresponding experimental measurements. The success of this novel reaction pathway lies in its ability to capture the abrupt decrease of the deposition rate at temperatures above 200 °C, which is attributed to the gas phase consumption of alane along with its increased desorption rate from the film surface.

      PubDate: 2017-12-27T05:46:41Z
  • A deterministic model for positional gradients in copolymers
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Ivan Kryven, Yutian R. Zhao, Kimberley B. McAuley, Piet Iedema
      A deterministic modelling approach is developed to predict the internal structure of gradient copolymer chains. A key innovation of the modelling approach is the introduction of a positional variable that gives direct access to quantitative gradient characteristics: the ensemble average composition and the gradient deviation. This positional variable is used to develop multi-dimensional population balance equations that can be solved numerically to calculate gradient quality measures. The methodology is illustrated using the gradient copolymerisation of ethylene and 1-octene via coordinative chain transfer mechanism, which is representative of a variety of polymerisation schemes for gradient copolymers. Simulation results are validated with those obtained by stochastic simulations which, until now, were the only means of predicting detailed gradient quality.
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      PubDate: 2017-12-27T05:46:41Z
  • Fischer-Tropsch synthesis in vertical, inclined and oscillating
           trickle-bed reactors for offshore floating applications
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Ion Iliuta, Faïçal Larachi
      Fischer-Tropsch synthesis performance in vertical, inclined and oscillating trickle-bed reactors for offshore floating applications was examined via a complex dynamic three-dimensional multiphase model based on volume-averaged mass, momentum, and species balance equations in liquid and gas phases and simultaneous diffusion and chemical reactions within the catalyst. Angular sinusoidal oscillatory motion of the trickle-bed reactor between vertical and an inclined position and between two inclined symmetrical/asymmetrical positions was examined. The behavior of inclined and oscillating Fischer-Tropsch trickle-bed reactors is atypical because the reactants in the main reactions originate from the gas phase and because a fraction of useful CO can be redirected in water gas-shift reaction. The performance of Fischer-Tropsch synthesis in the presence of water-gas shift reaction increases slightly with amplification of packed bed inclination even if the distortion of axial symmetry of liquid holdup and axial velocity radial distributions becomes considerable. Also, in asymmetric oscillating trickle-bed reactors the performance of Fischer-Tropsch synthesis is slightly improved. This enhancement is maximal for the reactor moving between vertical and an inclined position when the time-dependent waves of CO and H2 conversion develop around the steady-state solution of the middle inclination angle. The oscillatory Fischer-Tropsch performance moves towards the steady-state solution of the vertical state when the asymmetry between two inclined positions diminishes. Symmetric oscillating trickle-bed reactors generate an oscillatory Fischer-Tropsch performance around the steady-state solution of vertical state which is affected by the angular motion parameters of the reactor.

      PubDate: 2017-12-27T05:46:41Z
  • Modeling multiple chemical equilibrium in chiral extraction of metoprolol
           enantiomers from single-stage extraction to fractional extraction
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Panliang Zhang, Shichuan Wang, Kewen Tang, Weifeng Xu, Fan He, Yunren Qiu
      Enantioselective extraction of metoprolol (MT) enantiomers with di-cyclohexyl (D)-tartrate (DT) and boric acid (BA) as chiral extractant was performed. The process involving multiple chemical equilibrium is very complicated and the process optimization is difficult. On the basis of an interfacial reaction mechanism, a single-stage extraction model was established. The operation conditions of pH and DT to BA ratio were obtained through simulation and optimization of the equilibrium of the two phase extraction system. Based on the single-stage extraction model and the law of mass conservation, a fractional extraction model was established to simulate and optimize the fractional extraction process. To pursue a high productivity and reduce the required stages, a high feed to aqueous phase ratio (F/W = 1) and an asymmetric separation mode were applied. By asymmetric separation where the optical purity of the product in extract phase and raffiniate phase is not equal, enantiomeric excess (ee) value for the eutomer of MT can reach up to 98.64% and yield can reach up to 64.68% with 20 extraction stages.
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      PubDate: 2017-12-27T05:46:41Z
  • Polyimide-graphene oxide nanofiltration membrane: Characterizations and
           application in enhanced high concentration salt removal
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Nadiah Khairul Zaman, Rosiah Rohani, Abdul Wahab Mohammad, Arun Mohan Isloor
      A membrane usually suffers from a reduction in membrane rejection performance when exposed to a concentrated salt solution. A fabricated polyimide (PI)/graphene oxide (GO) mixed matrix membrane (MMM) was prepared at different GO/PI concentrations (ranging from 0 to 3.5 wt%) to investigate membrane performance in diluted and concentrated salt solutions. Results showed that the MMM possess nanofiltration (NF) properties with high water permeability and excellent salt rejection (99%) in diluted conditions regardless of the applied filtration pressure. The water and permeate permeability increased with the increase in GO content. Interestingly, for concentrated salt solutions, PI/GO MMM only showed at most 4% reduction in rejection, unlike in pure PI membrane, which experienced 16% reduction. A higher amorphous region of the MMM compared to the pure PI in salt solutions was found through XRD. The ionization of GO increases the amorphous structure thus enhances the effective thickness of membrane maintaining the MMM rejection performance. 0.9 wt% GO/PI in MMM showed the highest rejection (98%) in 0.15 M Na2SO4. The presence of GO with its unique properties and highly porous structure was found to retain the membrane rejection properties, especially in concentrated solution.

      PubDate: 2017-12-27T05:46:41Z
  • Intensification of high-phase-ratio extraction via microbubble-agitation
           in gas-liquid-liquid systems
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Ting-Fan Feng, Jing Tan, Wen-Sheng Deng, Yue-Feng Su
      Microbubble-agitated extraction was conducted with microextractors for process intensification of extraction with high phase ratio. Hexanoic-acid/water/n-octanol system with phase ratio of 80 was selected as a model system. Single and double membrane dispersion modules were developed for generating liquid–liquid and gas–liquid–liquid microdispersion systems. 10 different methods, 6 of which containing microbubbles, were designed to realize high-phase-ratio extraction. The effect of dispersion size, structure of gas–liquid–liquid emulsion and amount of microbubbles were systematically investigated. The most efficient and stable mode was recommended, with which Murphree efficiency could reach 90% in 0.5 s and the overall volumetric mass transfer coefficient ranges in 7.88–41.34 s−1, about 40 times greater than liquid–liquid system. The mechanism of the intensification effect by introducing microbubbles was discussed. Two typical gas–liquid–liquid structures were selected to study the effects of microbubbles in adjusting phase ratio and promoting turbulence in continuous phase. Two dimensionless equations were established to correlate mass tranfer coefficients respectively, both of which showed good coincidence with experimental data.
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      PubDate: 2017-12-27T05:46:41Z
  • Efficient simulation and equilibrium theory for adsorption processes with
           implicit adsorption isotherms – Ideal adsorbed solution theory
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): M. Fechtner, A. Kienle
      Recently an efficient method for the simulation of packed bed adsorbers with implicit adsorption isotherms was presented. It uses a method of lines approach and exploits standard software for the simultaneous solution of the resulting differential algebraic equations (DAEs). Application was demonstrated for stoichiometric ion exchange. In the present paper, the approach is extended to systems described by the adsorbed solution theory. For that purpose, the relation between the differential index of the DAE system and the spectral properties of the underlying adsorption equilibrium is established. In particular, it is shown that real and positive eigenvalues of the Jacobian of the underlying conservation equations will lead to a differential index of one. It is further shown that real and positive eigenvalues of the Jacobian related to the IAST can be guaranteed for binary mixtures with any type of pure component adsorption isotherm or for multicomponent mixtures with certain restricted types of pure component isotherms. The new method is illustrated for different explicit and implicit pure component adsorption isotherms belonging to this class. It is compared with alternative solution approaches using the modified FastIAS method by Do and Myers and semi-analytical solutions from equilibrium theory.

      PubDate: 2017-12-27T05:46:41Z
  • The Antoine equation of state: Rediscovering the potential of an almost
           forgotten expression for calculating volumetric properties of pure
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Eduard Araujo-Lopez, Juan Sebastian Lopez-Echeverry, Simón Reif-Acherman
      Antoine is mainly known for the equation usually used for predicting vapor pressure of pure compounds that bears his name. In this article we show a little known equation of state (EoS), as well as its functionality to predict current PvT properties of more than forty compounds including industrial, noble, and organic gases. The Antoine EoS has been parameterized in three regions: P r < 1.2 , 1.2 ⩽ P r ⩽ 10 and P r > 10 in order to improve its performance in the widest possible area. The proposed sets of optimized parameters were fitted by minimizing deviations after comparing predicted values with available experimental data in open literature. The volumes predicted with the optimized Antoine EoS have been compared with those calculated with the widely-known Soave-Redlich-Kwong (SRK), Peng-Robinson-Stryjek-Vera (PRSV2) and Valderrama-Patel-Teja (VPT) equations of state. Results obtained by using the optimized Antoine EoS show better accuracy in the zone of high reduced pressures for all compounds and, in a more general way, for most of the compounds in the remaining zones than the other equations of state. The extension to noble gases and other compounds originally not taken into account by Antoine have been successfully achieved.

      PubDate: 2017-12-27T05:46:41Z
  • Adsorption of simple square-well fluids in slit nanopores: Modeling based
           on Generalized van der Waals partition function and Monte Carlo simulation
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Lingli Kong, Hertanto Adidharma
      A model based on the Generalized van der Waals partition function is derived to predict the adsorption of square-well fluid in slit pores of any size, the walls of which also have square-well potential. The space inside the pore is divided into several regions based on the extent of the attractive regions generated by the walls. Closed-form expressions of the chemical potentials of the confined fluid in different regions in the pore are obtained. The densities of fluid in different regions are calculated by equalizing the chemical potentials of fluid in those regions to that of the bulk phase. To examine the accuracy of the model, the Grand Canonical Monte Carlo (GCMC) simulation is also conducted. We find that the model well captures the effects of the bulk conditions and the properties of adsorbate and pore on the density of adsorbate in the pore. The model is also shown to be able to predict the adsorption of real gases in various activated carbons.

      PubDate: 2017-12-27T05:46:41Z
  • Direct measurement of the contact angle of water droplet on quartz in a
           reservoir rock with atomic force microscopy
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Yajun Deng, Lei Xu, Hailong Lu, Hao Wang, Yongmin Shi
      The wettability of a reservoir rock is an important property affecting the states of fluids in pores that are constructed with minerals of various types. However, the mineral grains are usually micro-sized so that the traditional optical contact angle method is hard to be applied to study their wettabilities. Although some measurements have been carried out for the contact angles of liquids on mineral surfaces, those previous studies were mainly on flat artificial mineral surfaces. To understand the wettabilities of water on rough natural mineral surfaces, the contact angles of micro-sized water droplets on relatively rough quartz surfaces in a natural sand rock were measured with an atomic force microscopy (AFM). The results obtained show that the droplets were asymmetrical so that the contact angles, which were around 27.8–50.3°, were different along the triple-phase contact lines, probably due to surface roughness, heterogeneity, atomic arrangement, etc. As compared with previous studies, surface pretreatment and droplet size were regarded as the two key factors that caused the substantial difference in contact angles of water on quartz between the current and previous researches, which might imply that the present results could better describe the wettability of a natural reservoir rock.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Measurements of hydrocarbon bubble points in synthesized mesoporous
           siliceous monoliths
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Hyeyoung Cho, Dominic Caputo, Michael H. Bartl, Milind Deo
      Silica based crack-free monoliths having the same pore size range as the oil and gas producing north-american shales were synthesized using a new synthesis procedure. Crack-free monoliths were synthesized by controlling the evaporation rate. Evaporation rate of 0.4 g/cm2 was found optimal for making monoliths in cylindrical enclosures of different sizes for experimentation. The focus of this work was to understand the effects of nano-sized porous media on the saturation pressures of a hydrocarbon mixture of methane and decane. The physicochemical properties of the synthesized monoliths were measured using X-ray diffraction (XRD), nitrogen adsorption/desorption isotherm (BET), pore size distribution curve, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of decane in saturated monoliths revealed different boiling points in comparison to pure decane. The experimentally measured saturation pressures at two different temperatures of the bulk hydrocarbon mixture (decane-methane) matched well with the simulated results. The bubble point pressures of a hydrocarbon mixture in the nano-sized monolith were lower (about 18%) than those in the bulk.

      PubDate: 2017-12-27T05:46:41Z
  • Impact of phase saturation on wormhole formation in rock matrix acidizing
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Masoud Babaei, Majid Sedighi
      Studies of the rock matrix acidizing for enhanced recovery of oil or gas have entirely focused on the fully water saturated conditions. In fact, matrix acidizing can be conducted in low-water-cut oil-production wells without pre-flushing of water or in high water production by injecting gas or oil ahead of the acid injection. These conditions yield a multiphase system, where the dynamics of acid transport and reactions can be altered by the presence of an immiscible phase. Against this backdrop, we present an investigation of the impact of initial saturation of an immiscible phase in the damaged zone on the efficiency of wormhole generation and growth in acidizing operations. We present a dimensionless two-phase reactive transport modelling tailored for studying the processes associated with rock acidizing. For a case study of acid injection into calcite with random porosity and permeability distribution, we show that an initial two-phase condition has positive feedback on the generation of wormholes. The results, however, indicate that the relative magnitude of reduction in the amount of pore volume of injected acid to produce effective wormholes depends on the mobility ratio, so that a higher mobility ratio facilitates a faster wormhole generation process. Under the conditions of modelling study presented, we demonstrate that in addition to the commonly used pair of Péclet-Damköhler regime identification, the mobility ratio of the displacing/displaced fluids, the relative permeability and phase condition need be accounted for in the analysis, if there are two-phase flow conditions across the target region of acidizing.
      Graphical abstract image

      PubDate: 2017-12-27T05:46:41Z
  • Intrusive measurements of air-water flow properties in highly turbulent
           supported plunging jets and effects of inflow jet conditions
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Hang Wang, Nuryanto S. Slamet, Gangfu Zhang, Hubert Chanson
      A plunging jet is an efficient device to entrain gas into liquid flow. In many practical occasions, the gas entrainment needs to be carefully controlled, and the interaction between the shear flow turbulence and entrained bubbles has to be better understood. This paper presents a physical study of vertical supported two-dimensional plunging jets using a relatively large-size facility. The air-water flow and turbulence properties were measured with an intrusive phase-detection probe and a total pressure sensor simultaneously. The inflow pre-aeration and turbulence level of the falling jet were carefully characterised, and the effects of jet impact velocity and jet length on air entrainment in plunging pool were investigated. The experimental results were systematically compared to relevant studies. A discussion was developed on the quantification of turbulence intensity in highly-aerated flow based on total pressure measurement. The flow turbulence properties were derived respectively from the interfacial phase-detection signals and total pressure signals. The results highlighted difference in terms of the turbulence intensities between interfacial motions and water-phase turbulence. The present work showed that the jet impact velocity, jet length, inflow disturbance and pre-entrainment of air had considerable effects on air entrainment capacity and subsurface air-water flow properties in plunging jets hence should be carefully characterised in relevant studies.

      PubDate: 2017-12-27T05:46:41Z
  • Fluidized bed classification of particles of different size and density
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Jana Chladek, Chameera K. Jayarathna, Britt M.E. Moldestad, Lars-Andre Tokheim
      The main objectives of this study were to quantify the classification efficiency of a binary mixture of two different particle types and to demonstrate that CPFD can be used to simulate the main features of the classification process. A lab-scale cylindrical fluidized bed (8.4 cm inner diameter, 150 cm height), equipped with pressure sensors and a video camera for recordings, was applied in the experiments. The particles used in the study were ceramic beads (median diameter 70 µm, skeletal density 3830 kg/m3) and steel shot (290 µm, 7790 kg/m3). Ambient air was used as the fluidization medium. The minimum fluidization velocities of pure ceramic beads and steel shot were found to be 0.015 m/s and 0.240 m/s, respectively. In the experiments with a binary mixture of the two materials, the fluidization column was filled by alternating layers of ceramic beads and steel shot. In principle, segregation of the two particle types can be obtained by applying a suitable gas velocity within the interval defined by the two minimum fluidization velocities, resulting in a top layer of mainly lighter and smaller particles (flotsam) and a bottom layer of mainly heavier and larger particles (jetsam). In the experiments, the air velocity was gradually increased until the entire bed was fluidized. A gradual rearrangement of the multi-layer structure into a two-layer structure was observed. The rearrangement started at the top and then progressed downwards until most of the steel particles were collected at the bottom of the bed and practically all the ceramic beads were gathered at the top. The velocity at which the flotsam and jetsam layers were clearly segregated was found to be 0.180 m/s. The jetsam layer contained less than 0.3 wt% ceramic beads indicating that an almost pure steel shot fraction could be produced through fluidized bed classification. The flotsam layer was, however, less pure, with a steel shot content up to 24 wt%, suggesting that this layer may need a second classification stage for improved purity. Computational particle-fluid dynamics (CPFD) simulations of the same setup were performed using the commercial software Barracuda. The simulated minimum fluidization velocity of steel shot, applying the Ergun drag model, perfectly matched the experimental value. For the ceramic beads, however, the simulations, applying the Wen-Yu drag model, gave a value lower than the experimental value. Still, the simulations were able to capture the general behavior of the particles in the bed observed in the classification experiments, i.e. the rearrangement of the layers, even if a higher gas velocity was required for complete classification of the particles. The formation of air pockets was also observed in the simulations, as in some of the experiments. The results suggest that Barracuda CPFD simulations can be a useful tool in design and evaluation of fluidized bed classifiers.
      Graphical abstract image

      PubDate: 2017-12-13T09:48:03Z
  • Extension to multiple temperatures of a three-reaction global kinetic
           model for methane dehydroaromatization
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Y. Zhu, N. Al-ebbinni, R. Henney, C. Yi, R. Barat
      An alternative to flaring of surplus natural gas is methane dehydroaromatization (MDA) to benzene (C6H6) over a bifunctional molybdenum/zeolite catalyst. Byproducts include H2, C2H4, and naphthalene (C10H8). While an MDA detailed elementary reaction mechanism is now available, a simpler global kinetic model is more useful for engineering and screening calculations. A literature three-step reaction model exists but with rate constants only at 950 K. In the current work, Arrhenius parameters for the three global reactions have been determined over 948–1023 K based on a regression of major gas species concentration data generated from Chemkin® simulations of a packed bed reactor running the detailed MDA mechanism. In addition, the three-step model is used to illustrate the need to remove H2, perhaps through a membranous reactor wall, in order to overcome strong equilibrium CH4 conversion limitations. Such H2 removal, though, improves C10H8 selectivity at the expense of C6H6.

      PubDate: 2017-12-13T09:48:03Z
  • How chain length dependencies interfere with the bulk RAFT polymerization
           rate and microstructural control
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Nils De Rybel, Paul H.M. Van Steenberge, Marie-Françoise Reyniers, Dagmar R. D'hooge, Guy B. Marin
      A pseudo-steady state based (PSSA) deterministic solution strategy is presented to calculate the concentrations of single and multi-arm macrospecies types in reversible addition fragmentation chain transfer (RAFT) polymerization, accounting for chain length dependent apparent rate coefficients to fully reflect the impact of diffusional limitations. The simulation time is of minute scale and diffusional limitation on termination are accounted for with the RAFT-chain length dependent-termination technique. Based on an extensive set of experimental data (18 conditions), addition and fragmentation kinetic parameters are determined for RAFT polymerization of styrene initiated by 2,2′-azobis(2-methylpropionitrile) and 2-cyano-2-propyl dodecyl trithiocarbonate. Due to higher chain length dependent apparent termination rates, a rate retardation with respect to the free radical polymerization (FRP) results despite that a simplified degenerative mechanism can be considered. This rate retardation is enhanced for polymerizations exhibiting a stronger gel-effect (e.g. methyl methacrylate). Then even the average RAFT polymerization characteristics cannot be reliably calculated by approximating the macroradical chain length distribution (CLD) through a Poisson or Schulz-Flory distribution. The calculation of the macroradical CLD always requires a full kinetic model taking into account the chain length dependencies for all individual chain lengths.

      PubDate: 2017-12-13T09:48:03Z
  • Lattice-Boltzmann flow simulation of an oil-in-water emulsion through a
           coalescing filter: Effects of filter structure
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Yasushi Mino, Ayano Hasegawa, Hiroyuki Shinto, Hideto Matsuyama
      The permeation of an oil-in-water (O/W) emulsion through a coalescing filter was numerically studied using the lattice Boltzmann method (LBM). A numerical simulation model for the coalescing phenomena was developed based on the free-energy LBM. We investigated the effects of the wettability of fibers, filter porosity, and fiber diameter on the coalescing behaviors by performing two-dimensional permeation simulations for the O/W emulsions through modeled fibrous filters. We mainly focused on hydrophilic filters because they did not generate small secondary droplets during oil droplet detachment from the filter, and this is preferred for precise separation of oil and water. Our simulations demonstrated that filters with larger pore spacings enable formation of larger droplets but allow more droplets to pass without coalescing. To solve this problem, we designed bi-layered filters composed of a small-pore filter to accurately catch the droplets and a large-pore filter to enlarge the droplets; we demonstrated the effectiveness of the bilayer structure for membrane coalescence.

      PubDate: 2017-12-13T09:48:03Z
  • An experimental investigation of the probability distribution of turbulent
           fragmenting stresses in a high-pressure homogenizer
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Andreas Håkansson
      The high-pressure homogenizer (HPH) is, together with the rotor–stator mixer (RSM), the standard equipment for emulsification in many fields of chemical processing. Both give rise to intense turbulence which, in turn, gives rise to drop breakup. Previous investigations focus on average turbulent disruptive stress. However, turbulence is a stochastic phenomenon and drop breakup will be characterized by instantaneous stresses, or more specifically by the probability distribution of instantaneous turbulent stresses. This study uses high-resolution particle image velocimetry (PIV) data to measure the probability distribution of turbulent stresses in the HPH. It is concluded that stress distributions approximately follow a lognormal model and that the skewness of the distributions decreases with increasing distance from the gap exit until a constant distribution shape is obtained at the position where the turbulence is fully developed. This converged stress distribution is similar to that obtained for RSMs in previous studies, suggesting that stress distribution shape is a general property. Moreover, large differences are observed when comparing these experimental stress distributions to the most widely used expression for describing this stochastic effect in fragmentation rate models. This indicates that the traditionally used fragmentation rate models can be fundamentally flawed, at least in relation to RSM and HPH emulsification.
      Graphical abstract image

      PubDate: 2017-12-13T09:48:03Z
  • A dual grid, dual level set based cut cell immersed boundary approach for
           simulation of multi-phase flow
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Tejas Patel, Absar Lakdawala
      A numerical methodology based on dual grid dual level set function is presented for simulating 2D multiphase flows through complex geometries on a non-body fitted Cartesian computational grid. A Cut Cell based immersed boundary method (IBM) is used to sharply resolve complex geometries. The cut cells near the immersed boundary are identified using a fictitious level set function. The governing equations are discretized using the finite volume method (FVM) on a m × n staggered grid. The dynamics of fluid-fluid interface is tracked by an other level set function defined on dual grid (2m × 2n). The use of dual grid arrangement for fictitious level set function results in an accurate calculation of diffusion and advection fluxes at the cut cell near the immersed boundary. A module by module validation of the developed numerical methodology is carried out with several test cases. Two single phase flow problems corresponds to Poiseuille flow and flow through a convergent-divergent section while the two multiphase problems selected are the standard Young’s Laplace law test – semicircular fluid rod on a horizontal surface – and the bubble rise phenomenon in an inclined channel. The obtained results show an excellent agreement with those derived analytically or taken from literature. Furthermore, the performance study carried out on the present model shows that the method is between first and second order accurate.

      PubDate: 2017-12-13T09:48:03Z
  • Investigations about the effect of fractal distributors on the
           hydrodynamics of fractal packs of novel plate and frame designs
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Gongqiang He, Vadim Kochergin, Yuehao Li, Krishnaswamy Nandakumar
      Flow distributors are extensively adopted by chemical industry to distribute process fluid for the downstream equipment. Conventional flow distributors in general have limited number of outlets. Their low outlet densities cannot distribute the incoming process stream uniformly and efficiently, which consequently undermine the overall equipment performance. In contrast, fractal distributors can achieve high outlet densities because of their inherent self-similarity feature. In this study, we fabricated two fractal packs of novel plate and frame designs. Each fractal pack was comprised of a fractal distributor, a resin bed and a fractal collector. The fractal distributors/collectors in these two fractal packs have 256 and 16 outlets/inlets, respectively. In this study, we carried out both CFD modeling and experiments to understand the effect of outlet density on the hydrodynamics of the downstream resin bed. By comparing the predicted velocity fields and the measured residence time distribution (RTD) curves, we noticed that a fractal distributor of high outlet density can distribute the process stream uniformly at a low pressure drop to the resin bed. The process streams entering the resin bed reach plug flow profile within a short bed depth. As a result of the uniform flow distribution, mal-distribution such as channeling and dead space are minimized, and the process streams have a uniform RTD in the fractal pack. In comparison, the fractal distributor of low outlet density, which mimics some aspects of a conventional distributor, is found to have severe mal-distribution in the resin bed and consequently poor RTD inside the fractal packs. In addition, the RTD analysis confirms that the fractal distributor of high outlet density shows consistently good distributing performance for a wide range of operating flow rates. This study confirms the advantages of fractal distributors over conventional ones and demonstrates the benefit of fractal distributors in improving the overall performance of chemical equipment, indicating that fractal distributors are promising to enable process intensification for the chemical industry.

      PubDate: 2017-12-13T09:48:03Z
  • Evaluation of contact force models for discrete modelling of ellipsoidal
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Kamyar Kildashti, Kejun Dong, Bijan Samali, Qijun Zheng, Aibing Yu
      Discrete element method (DEM) has been widely used to study granular materials. However, how to model non-spherical particles is still challenging. Ellipsoidal particles are a typical kind of non-spherical particles in DEM simulations. There are three common methods to calculate the overlap and contact force between two ellipsoidal particles, namely, geometric potential (GP), common normal (CN) and overlap region (OR) methods. These methods are based on different physical concepts and hence will give different results. However, the comprehensive evaluation of these methods is still lacking, leaving DEM users no solid reference for selecting algorithms. In this paper, we conduct detailed comparisons on the penetration depth, contact plane and contact point predicted by the three methods. Particularly, using the orientation discretization method, the results are compared in all orientations quantitatively. It is shown that the difference between GP and CN is the largest whereas OR is always in between. The difference in contact point is relatively small when overlap ratio is small, whereas the difference in contact plane can always be large. Further, the results are directly compared to those obtained from sub-particle scale finite element analyses, which reveals that CN can always accurately predict contact plane and most times contact point, while GP are relatively better in predicting force magnitude. This study not only gives a more clear and comprehensive evaluation of different contact force models for ellipsoidal particles but also establishes an effective framework for comparing and verifying contact force models for general non-spherical particles.
      Graphical abstract image

      PubDate: 2017-11-15T18:06:36Z
  • Oxygen permeation properties of novel BaCo0.85Bi0.05Zr0.1O3−δ
           hollow fibre membrane
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Zhenghui Qiu, Yadi Hu, Xiaoyao Tan, Siti Salwa Hashim, Jaka Sunarso, Shaomin Liu
      In this work, we characterized and tested the oxygen permeation properties of BaCo0.85Bi0.05Zr0.1O3−δ (BCBZ) hollow fibre membranes fabricated by a combined phase inversion for spinning and sintering route using polyetherimide (PEI) as the polymer binder. The powder X-ray diffraction results showed that the BCBZ powder for spinning had to be calcined at around 950 °C to form a hexagonal phase structure, while the hollow fibre precursors were sintered at 1150–1200 °C to form the cubic perovskite structure for oxygen permeation. It displayed the highest oxygen flux of 7.3 cm3 (STP) cm−2 min−1at 950 °C under an air/He gradient. The theoretical correlation of the oxygen fluxes at different operating conditions showed that the oxygen permeation through BCBZ fibre was limited by surface exchange reactions. Carbon dioxide (CO2) resistance of BCBZ hollow fibre was tested by exposing it to alternating different sweep gas containing helium (He), 20% CO2 in He, 80% CO2 in He, and pure He. Despite the significant reduction in oxygen fluxes upon subjected to CO2-containing sweep gases due to the strong CO2 sorption on the membrane surface, no permanent damage on the membrane was detected and the original flux could be recovered at the end of the 105-h test once the sweep gas was switched back to helium. This result clearly highlights the high CO2 resistance of BCBZ hollow fibre membrane due to the presence of Zr4+ with higher acidity than Co2+ in BCBZ perovskite lattice. High CO2 tolerance enables the membrane use as membrane reactors for more advanced applications where the presence of CO2-containing atmosphere is unavoidable.

      PubDate: 2017-11-15T18:06:36Z
  • Experimental investigation of mass transfer performance in laboratory- and
           pilot-scale structured-packing columns under roll motion
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Xiao-ning Di, Shu-jie Chen, Wen-hua Wang, Yi Huang
      Influence of roll motion on the mass transfer performance in laboratory- and pilot-scale structured-packing columns was investigated. A six-degree-of-freedom motion parallel platform was adopted to mimic different sea states of roll motion, and the relative change in the mass-transfer area caused by roll motion was obtained using an air-NaOH system. The experimental results showed that both enhanced and deteriorative mass transfer phenomena could be induced by roll motion, which results from the combined effect involving the operating conditions, packing types and sea states. Based on these results, a nominal maximum rolling velocity was proposed. The nominal maximum rolling velocity was positively correlated with the relative change in the mass-transfer area. Furthermore, the results indicated that tilt could be regarded as an extreme sea state of roll motion.

      PubDate: 2017-11-15T18:06:36Z
  • Kinetic modeling of CO2 adsorption on an amine-functionalized solid
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Wonho Jung, Junhyung Park, Kwang Soon Lee
      A kinetic model of CO2 adsorption on an amine-functionalized silica sorbent, 0.37EB-PEI, was proposed by using experimental data from a miniature isothermal fixed bed reactor system called Autochem. Breakthrough curve tests were conducted at different CO2 concentrations and different temperatures to acquire experimental data under adsorption-dominant conditions. Additionally, temperature programmed desorption (TPD) experiments were carried out for different CO2 concentrations with different starting temperatures to investigate the desorption kinetics. A modified Langmuir kinetic equation was found to provide a satisfactory representation of the adsorption-dominant experimental data, including the long tails. A separate kinetic model was proposed to express the desorption-dominant TPD data. The dynamic effects of the empty volume in the Autochem device on the experimental measurements were rigorously handled through separate empty-volume dynamic tests.

      PubDate: 2017-11-15T18:06:36Z
  • Measurement of gas phase characteristics in vertical oil-gas-water slug
           and churn flows
    • Abstract: Publication date: 23 February 2018
      Source:Chemical Engineering Science, Volume 177
      Author(s): Da-Yang Wang, Ning-De Jin, Yun-Feng Han, Fan Wang
      In the present study, gas phase characteristics of oil-gas-water slug and churn flows in a vertical upward pipe with 20 mm inner diameter (ID) are experimentally investigated. We firstly measure the fluctuating signals of a traversable bi-optical fiber probe at different radial positions. The gas phase flow parameter distributions (local gas velocity, local gas holdup) are obtained and the flow structure is uncovered by calculating the series of gas bubble chord lengths at different radial positions. Additionally, in order to describe the flow structure of slug flow, the relative length of the liquid slug, the profile distributions of gas holdup and bubble size in liquid slug are investigated. To understand the nonlinear dynamic characteristics of slug and churn flows, multi-scale cross entropy (MSCE) algorithm is applied to analyze the signals of a high-resolution half-ring conductance sensor and bi-optical fiber probe. The result indicates that multi-scale cross entropy can be an effective tool for validating the measurement of gas phase characteristics by using the traversable bi-optical fiber probe.

      PubDate: 2017-11-15T18:06:36Z
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